What does "ii" mean in "dpkg --list" command output?

Question

What is the significance/meaning of ii at the beginning of the output of

dpkg --list 

command?

dpkg --list | grep firefox

for example, returns ii firefox together with other information.

Solution

The first i is the desired action, i stands for install.

The second i is the current package status, i stands for installed.

From man dpkg-query:

The first three columns of the output show the desired action, the package status, and errors, in that order.

Desired action:

            u = Unknown
            i = Install
            h = Hold
            r = Remove
            p = Purge

Package status:

            n = Not-installed
            c = Config-files
            H = Half-installed
            U = Unpacked
            F = Half-configured
            W = Triggers-awaiting
            t = Triggers-pending
            i = Installed

Error flags:

           <empty> = (none)
            R = Reinst-required